Yes, Germany was the birth place of Martin Luther and Protestantism, but Germany had long since ceased to be a nation driven by the Word of God. Germany was a nation that was complacent in its religion and because of this, because of this false confidence in their own spirituality, the people of Germany were not prepared to withstand or even fully comprehend the evils perpetuated by the Nazi party. For many Germans Christianity was a fact, not a practice. It was a birth rite, not a gift of grace. Because of this, and because of a fierce loyalty to the idea of the German nation, there were few in Germany who were willing to oppose Hitler, and this troubled Bonhoeffer greatly.
For Bonhoeffer, the problem was a misunderstanding of grace. He believed that most of his countrymen had a view he called, "cheap grace," the idea that salvation didn't require anything of the believer. Bonhoeffer however, vehemently disagreed. Instead, he argued that grace was costly. He said:
"Costly grace is the gospel which must be sought again and again and again, the gift which must be asked for, the door at which a man must knock. Such grace is costly because it calls us to follow and it is grace because it calls us to follow Jesus Christ. It is costly because it costs a man his life, and it is grace because it gives a man the only true life. It is costly because it condemns sin, and grace because it justifies the sinner. Above all, it is costly because it cost God the life of his Son...and what has cost God so much cannot be cheap for us."Bonhoeffer insisted that a life lived in fear or inaction was no Christian life at all, it was a misunderstanding of what grace is. Christians must conform their lives to that of Christ because a dear price was paid so that we could have the ability to do so. Therefore, Christians must advocate for the oppressed because that is how Christ lived his life. Christians must oppose evil because we are to be a light in the world. Bonhoeffer said, "We are not simply to bandage the wounds of victims beneath the wheels of injustice, we are to drive a spoke into the wheel itself." This is action. This isn't complacency. The grace shown to the Christian should compel us to action, for the benefit of both the oppressed and the oppressor.
I personally, find the message of Bonhoeffer to be incredibly convicting. It's easy to ignore the injustice and the evil in the world, and it is even easier to think only of the benefit that Christ's grace brings to me.